A system described in Japanese Unexamined Patent Publication No. 2012-111635 is known as a conventional conveyance storage system. The transport system described in JP '635 includes: a first track that passes above loading ports of processing devices; an overhead traveling vehicle traveling along the first track and including a hoist; a second track under and in parallel or substantially parallel to the first track, the second track passing above the load ports; a buffer for placement of the carrier, the buffer being provided under the second track at a position higher than the loading port, and being arranged to allow the carrier pass in a vertical direction over the loading port; and a local vehicle traveling along the second track and including a hoist to perform delivery and receipt of the carrier between the buffer and the loading port.
It is a conventional technique that the first track is provided between processes and that the carrier is conveyed between the processes by the ceiling traveling vehicle. However, the travel path that the ceiling traveling vehicle can take is limited in the track; another ceiling traveling vehicle blocks the travel path, for example, to hinder the travel of the ceiling conveyance vehicle behind, which may reduce inter-process conveyance efficiency.
It could therefore be helpful to provide a conveyance system that can improve inter-process carrier conveyance efficiency.